In his seminal 1990 article “The Perils of Presidentialism,” political scientist Juan Linz pointed out that “the vast majority of the stable democracies in the world today are parliamentary regimes” and that, in contrast, “the only presidential democracy with a long history of constitutional continuity is the United States.” Based in part on this observation, Linz concluded that parliamentary democracies are more conducive to stable democracies that presidential democracies.
Linz thought the United States was the exception. What, according to Linz, made the United States exceptional? His answer was that it lacked political polarization and instead had a large moderate consensus that avoided catering to extremists. But this is no longer true.